1. Field of the Invention
This invention relates to an exposure apparatus. This invention particularly relates to an exposure apparatus for recording an image, which is represented by a digital signal, on a photosensitive material.
2. Description of the Prior Art
Exposure apparatuses for recording an image, which is represented by a digital signal, on a photosensitive material, wherein a rotating member referred to as a rotating polygon mirror is utilized, have heretofore been known. The rotating polygon mirror is provided with plane reflecting surfaces at the periphery for reflecting light, which has been produced by a light emitting device, such as a laser or a light emitting diode (LED), onto a material to be scanned with the light.
Also, an image-wise exposure apparatus has heretofore been proposed, wherein image signals having been obtained by being divided into a plurality of optical wavelength regions are converted into optical signals of colors corresponding to the respective optical wavelength regions, and the optical signals are radiated from an exposure head through a SELFOC lens array (SELFOC lens; trade name) onto photographic paper. The image-wise exposure apparatus is disclosed in, for example, Japanese Patent No. 2867936. In the disclosed image-wise exposure apparatus, optical fibers are utilized for optical transmission.
However, the exposure apparatus in which the rotating polygon mirror is utilized has the problems in that the exposure unit itself is expensive, and high precision parts and high accuracy of assembling operations are required.
The primary object of the present invention is to provide an exposure apparatus, which has a simple structure and is capable of being produced at a low cost.
Another object of the present invention is to provide an exposure apparatus, the size of which is capable of being kept small.
The present invention provides a first exposure apparatus, comprising:
i) a light source section, which is constituted of a plurality of arrayed light source units, each of the light source units comprising:
a) multiple kinds of light emitting devices, which produce light beams having wavelengths falling within different wavelength ranges, and
b) an optical system for combining the light beams, which have been radiated out from the multiple kinds of the light emitting devices, with one another to form a combined light beam, and converging the combined light beam onto one end of an optical fiber,
ii) an exposure head, which is located so as to stand facing a photosensitive surface of a photosensitive material capable of being conveyed, and to which the other end of the optical fiber is connected, and
iii) a driving mechanism for moving the exposure head in a straight line along a direction, which is normal to the direction of conveyance of the photosensitive material.
In the first exposure apparatus in accordance with the present invention, the multiple kinds of the light emitting devices should preferably be constituted of light emitting diodes, which produce a red light beam, a green light beam, and a blue light beam respectively.
The present invention also provides a second exposure apparatus, comprising:
i) a light source for producing a light beam,
ii) a light modulating section, which is constituted of a plurality of arrayed light modulating units, each of the light modulating units comprising:
a) multiple kinds of filtering devices, which perform filtering operations on the light beam having been radiated out from the light source such that the filtering devices transmit light components of the light beam having wavelengths falling within different wavelength ranges, and each of which radiates the corresponding transmitted light component into one end of an optical fiber of an optical fiber group, and
b) a plurality of light modulating devices, each of which modulates the light beam incident upon the corresponding one of the filtering devices,
iii) an exposure head, which is located so as to stand facing a photosensitive surface of a photosensitive material capable of being conveyed, and to which the other end of each optical fiber of the optical fiber group is connected, and
iv) a driving mechanism for moving the exposure head in a straight line along a direction, which is normal to the direction of conveyance of the photosensitive material.
In the second exposure apparatus in accordance with the present invention, the multiple kinds of the filtering devices should preferably be constituted of dichroic filters, which transmit a red light component, a green light component, and a blue light component respectively. Also, each of the light modulating devices should preferably be constituted of a liquid crystal device.
As described above, the first exposure apparatus in accordance with the present invention comprises the light source section constituted of the plurality of the arrayed light source units, each of which comprises the multiple kinds of the light emitting devices, such as three-color light emitting diodes (LED""s). The first exposure apparatus in accordance with the present invention also comprises the exposure head, the driving mechanism for moving the exposure head in a straight line, and the optical fibers connected between the light source units and the exposure head. Therefore, with the first exposure apparatus in accordance with the present invention, the structure of the exposure apparatus can be kept simple, and the cost of the exposure apparatus can be kept low.
Also, as described above, the second exposure apparatus in accordance with the present invention comprises the light modulating section constituted of the plurality of the arrayed light modulating units, each of which comprises the multiple kinds of the filtering devices, such as dichroic filters. Each of the filtering devices transmits only the red light component, the green light component, or the blue light component, and filters out the other light components. Each of the light modulating units also comprises the plurality of the light modulating devices, such as the liquid crystal devices, each of which modulates the light beam incident upon the corresponding one of the filtering devices. The second exposure apparatus in accordance with the present invention also comprises the exposure head, the driving mechanism for moving the exposure head in a straight line, and the optical fiber groups connected between the light source and the exposure head. Therefore, with the second exposure apparatus in accordance with the present invention, as in the first exposure apparatus in accordance with the present invention, the structure of the exposure apparatus can be kept simple, and the cost of the exposure apparatus can be kept low.
Further, with the first and second exposure apparatuses in accordance with the present invention, the optical fibers, which can be bent freely, are employed as the light transmission paths. Therefore, the advantages can be obtained in that the size of the exposure apparatus can be kept small, and the light transmission paths are not affected adversely by dust, or the like.